Visual conditioning of the sting extension reflex in harnessed honeybees

Abstract

SUMMARYVisual performances of honeybees have been extensively studied using free-flying individuals trained to choose visual stimuli paired with sucrose reward. By contrast, harnessed bees in the laboratory were not thought to be capable of learning a Pavlovian association between a visual stimulus (CS) and sucrose reward (US). For reasons as yet unknown, harnessed bees only learn visual cues in association with sucrose if their antennae are ablated. However, slow acquisition and low retention performances are obtained in this case. Here, we established a novel visual conditioning protocol, which allows studying visual learning and memory in intact harnessed bees in the laboratory. This protocol consists of conditioning the sting extension reflex (SER) by pairing a visual stimulus (CS+) with an electric shock punishment (US), and a different visual stimulus (CS-) with the absence of shock. Bees with intact antennae learned the discrimination between CS+ and CS-by using chromatic cues, achromatic cues or both. Antennae ablation was not only unnecessary for learning to occur but it even impaired visual SER conditioning because of a concomitant reduction of responsiveness to the electric shock. We thus established the first visual conditioning protocol on harnessed honeybees that does not require injuring the experimental subjects. This novel experimental approach opens new doors for accessing the neural correlates of visual learning and memory in honeybees.

Invertebrate learning and memory: Fifty years of olfactory conditioning of the proboscis extension response in honeybees

“…Following the theoretical framework developed as a result of 50 years of PER conditioning, a novel protocol was recently established to enrich the spectrum of learning studies in the honeybee: the conditioning of the sting extension response (SER) (Vergoz et al 2007;Mota et al 2011b). In its original olfactory version, each bee is restrained in an individual harness such that a bridge is built between two metallic plates through which a mild electric shock is delivered (Vergoz et al 2007).…”

“…Such expectations are supported by a unique achievement that PER conditioning was unable to provide: the possibility of using visual stimuli as CSs and establishing thereby a visual version of SER conditioning (Mota et al 2011b). It is, indeed, possible to condition SER by pairing a visual stimulus (CS+) with an electric shock punishment (US) and a different visual stimulus (CS2) with the absence of shock in intact harnessed bees (Mota et al 2011b). Bees with intact antennae learn the discrimination between CS+ and CS2 by using chromatic cues, achromatic cues, or both.…”

Standard methods for behavioural studies ofApis mellifera

“…Both in the field and under the controlled conditions of a laboratory, bees reliably learn and remember odours, shapes and surface structures. Learning of colours is much more complicated under laboratory conditions (Gerber and Smith, 1998;Mota et al, 2011). Bees can be trained in classical and operant conditioning paradigms.…”

“…The bee is harnessed between two electrodes and after a number of odour-shock pairings the sting extends to the odour (Vergoz et al, 2007;Carcaud et al, 2009;Giurfa et al, 2009;Mota et al, 2011). In contrast to the shuttle box conditioning studies, which involve some type of consequence consistent with operant conditioning (escape, punishment, avoidance), the sting extension procedure is an application of classical conditioning and can be classified as an example of "fear" conditioning.…”

“…Recently, the sting response assay was used to demonstrate that bees learn well to differentiate between different colours under laboratory conditions, which otherwise inhibit visual learning (Mota et al, 2011).…”